The Internet has grown from a sparse collection of interconnected research institutions into a vast global network including information on nearly any topic imaginable. The sheer volume of the information that is available can sometimes present problems in obtaining desired information. Internet search engines offer a solution for finding desired information by providing a user interface for performing a search of a periodically updated index of information available on the Internet. Search engines generally accept one or more keywords from users, identify a set of results based on a comparison of the keywords to one or more indices, and return a list of identified results, such as web page URLs, to the user.
Search engines can aid greatly in locating information, but in some instances the search results provided either do not include the sought for information and/or the sought for information can not easily be discerned from the query result listings. For example, a simple single keyword search can return hundreds or even thousands of listings, while a detailed multiple keyword search may not return any results at all. Performing a series of searches with progressively narrowing keyword scope can sometimes be effective, but often there is a threshold at which there is concern that valid results are being omitted, and in some cases the sought for information may not be available on the Internet at all due to its specificity.